Method for establishing data connection on mobile network, mobile network, and policy control entity

ABSTRACT

A method for establishing data connections on a mobile network, a mobile network, and a policy control entity are disclosed. The method includes: establishing a data channel between a user equipment (UE) and a gateway (GW), and allocating an Internet Protocol (IP) address to the UE according to an address allocation request or a data channel setup request sent from the UE; and triggering the policy control entity to establish or update a policy control session according to the IP address. By using the mobile network and the policy control entity under the present invention, after the data channel is established between the UE and the GW, the GW may trigger the policy control entity to establish or update a policy control session.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/CN2009/070059, filed on Jan. 7, 2009, which claims priority toChinese Patent Application No. 200810003912.9, filed on Jan. 11, 2008,both of which are hereby incorporated by reference in their entireties.

FIELD OF THE INVENTION

The present invention relates to a communications technology, and inparticular, to a method for establishing data connections on a mobilenetwork, a mobile network, and a policy control entity.

BACKGROUND OF THE INVENTION

On an evolved packet system (EPS) network, user equipment (UE) accessesan evolved packet core (EPC) through a serving gateway (SGW) on a radioaccess network, and accesses an external packet data network (PDN)through a PDN GW. A policy control entity may dynamically generate aservice data policy rule according to service information about the UE,and send the service data policy rule to the PDN GW and the SGW, thusimplementing service-level dynamic policy control on the data.

In the prior art, the process of establishing a data connection toaccess a PDN by the UE includes: the SGW forwards a connection setupmessage sent from the UE to a PDN GW that corresponds to the PDN; thePDN GW returns a connection setup ACK to the SGW; the SGW returns aresponse indicating the completion of data connection setup to the UE.

The SGW may be a network element (NE) where a control plane and a userplane are separated or integrated. For example, the SGW may be amobility management entity (MME) or a GW on the EPS network, or anintegrated serving GPRS support node (SGSN) on a third generation (3G)network.

During the implementation of the present invention, the inventordiscovers the following problems in the prior art: When the UE accessesthe core network for the first time, the UE may not request theallocation of an Internet Protocol (IP) address but requests only thesetup of a data channel. If the network needs to implement policycontrol, the prior policy control procedures related to the EPS networkdata connection are not applicable to scenarios where no IP connectionis established for the data channel between the UE and the PDN GW. Thisis because the prior policy control session is connected over IP. Inaddition, for the mobility management protocol between GWs, the priorart is applicable to only the GPRS Tunneling Protocol (GTP) notrequiring an IP address and is inapplicable to the mobile IP protocol.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide a method for establishingdata connections on a mobile network, a mobile network, and a policycontrol entity. Thus, after a data channel is established between a UEand a GW, the GW triggers the policy control entity to establish orupdate a policy control session.

The technical solution of the present invention is as follows:

A method for establishing data connections on a mobile network includes:

establishing a data channel between a UE and a GW;

allocating an IP address to the UE according to an address allocationrequest or a data channel setup request sent from the UE; and

sending a policy control session setup or update request carrying the IPaddress to a policy control entity so that the policy control entityestablishes or updates a policy control session according to the policycontrol session setup or update request.

A policy control entity includes:

a receiving unit, configured to receive a policy control session setupor update request carrying a data channel ID from a GW;

an establishing unit, configured to establish a policy control sessionaccording to the data channel ID carried in the policy control sessionsetup request; and

an updating unit, configured to update an IP address and a policycontrol rule of the policy control session according to the policycontrol session update request.

A mobile network includes:

a GW, configured to: establish a data channel with a UE, allocate an IPaddress to the UE according to an address allocation request or a datachannel setup request sent from the UE, and send a policy controlsession setup or update request carrying the IP address to a policycontrol entity; and

the policy control entity, configured to establish or update a policycontrol session according to the policy control session setup or updaterequest.

By using the method for establishing data connections on a mobilenetwork, the mobile network, and the policy control entity provided inembodiments of the present invention, after a data channel isestablished between the UE and the GW, the GW triggers the policycontrol entity to establish or update the policy control session. Whenthe UE obtains an IP address through the PDN GW, the PDN GW establishesor updates the policy control session; or when the UE obtains an IPaddress through the SGW, the SGW establishes a mobile IP connection withthe PDN GW and then establishes or updates the policy control session.In embodiments of the present invention, the policy control can still beimplemented when the UE does not request the allocation of an IPaddress. Thus, embodiments of the present invention are applicable tothe GTP protocol and the mobile IP protocol.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows network architecture that supports service-level dynamicpolicy control on a next generation mobile communication network;

FIG. 2 is a flowchart of a method for establishing a data connection inan embodiment of the present invention;

FIG. 3 is a schematic diagram illustrating a process of establishing adata connection in Embodiment 1 of the present invention;

FIG. 4 is a schematic diagram illustrating a process of establishing adata connection in Embodiment 2 of the present invention;

FIG. 5 is a schematic diagram illustrating a process of establishing adata connection in Embodiment 3 of the present invention;

FIG. 6 is a schematic diagram illustrating a process of establishing adata connection in Embodiment 4 of the present invention;

FIG. 7 shows architecture of a mobile network in an embodiment of thepresent invention;

FIG. 8 shows a structure of a mobile network in Embodiment 4 of thepresent invention;

FIG. 9 shows a structure of a mobile network in Embodiment 5 of thepresent invention; and

FIG. 10 shows a structure of a mobile network in Embodiment 6 of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention provide a method for establishingdata connections on a mobile network, a mobile network, and a policycontrol entity. Thus, after a data channel is established between the UEand the GW, the GW triggers the policy control entity to establish orupdate the policy control session. For better understanding of theobjective, technical solution and merits of the present invention, thefollowing describes the present invention in detail with reference tothe accompanying drawings and exemplary embodiments.

FIG. 1 shows network architecture that supports service-level dynamicpolicy control on a next generation mobile communication network. FIG. 2is a flowchart of a method for establishing data connections in anembodiment of the present invention. The method includes the followingsteps:

Step 201: A data channel is established between the UE and the GW.

Step 202: The GW allocates an IP address to the UE according to anaddress allocation request sent from the UE.

Step 203: The GW triggers the policy control entity to establish orupdate the policy control session according to the IP address.

In step 201, the process of establishing a data channel between the UEand the GW may include: establishing a data channel between the UE andthe PDN GW; or establishing a data channel between the UE and the SGW.The UE sends an IP address allocation request, for example, a DynamicHost Control Protocol (DHCP) message, to request the allocation of an IPaddress for accessing the PDN. The PDN GW sends an IP address allocationresponse that carries the allocated IP address.

In step 202, the process of triggering the policy control entity toestablish or update the policy control session by the GW according tothe IP address may include: establishing a policy control sessionbetween the PDN GW and the policy control entity; or establishing apolicy control session between the SGW and the policy control entity; orestablishing a policy control session between the PDN GW or the SGW andthe policy control entity, and then updating the policy control rule bythe policy control entity according to the allocated IP address.

FIG. 3 is a schematic diagram illustrating a process of establishing adata connection in Embodiment 1 of the present invention. The processincludes the following steps:

Step 301: A UE establishes a data channel with a PDN GW, for example, anattach connection with the UE. The UE does not request the allocation ofan IP address in the attach request. The network establishes a GTPbearer by using the GTP mobility management protocol. In the connectionsetup process, the U E obtains the connection related configurationinformation that may include a bearer control mode.

Step 302: The UE sends an address allocation request (for example, aDHCP request) to the PDN GW, requesting the allocation of an IP addressfor accessing the PDN. The PDN GW allocates the address according to theaddress allocation request, including allocating the IP address by thePDN GW itself or allocating the IP address to the UE through otherservers or GWs.

Step 303: The PDN GW sends an address allocation response that carriesthe allocated IP address to the UE. In addition, the address allocationresponse may carry the PDN configuration information, including a domainname service (DNS) address, a proxy-call session control function(P-CSCF) address, and an application server address.

Step 304: The PDN GW sends a policy control session setup request to apolicy control entity according to the IP address, requesting toestablish a policy control session of this IP connection.

Step 305: The policy control entity establishes a policy control sessionaccording to the IP address carried in the policy control session setuprequest.

In step 305, the policy control entity may also send the policy controlrule of the IP connection to the PDN GW.

Step 303 may be executed before or after step 304. Step 303 is optional.

FIG. 4 is a schematic diagram illustrating a process of establishing adata connection in Embodiment 2 of the present invention. The processincludes the following steps:

Step 401: A UE establishes a data channel with a PDN GW. The PDN GWestablishes a policy control session a policy control entity. The PDN GWprovides the policy control entity with a data channel ID. The datachannel ID includes a UE ID and an ID that is used for accessing thePDN. The policy control entity may send related policy control ruleinformation to the PDN GW. The policy control rule information may beused for establishing a data channel, for example, reserving bandwidthresources for the data channel. In the data connection setup process,the UE may also obtain the connection related configuration informationfrom the PDN GW, for example, the bearer control mode.

Step 402: The UE sends an address allocation request, requesting theallocation of an IP address for accessing the PDN. After receiving therequest, the PDN GW allocates an IP address to the UE, includingallocating an IP address by the PDN GW itself or forwarding the requestto other servers or GWs.

Step 403: The PDN GW sends an address allocation response that carriesthe allocated IP address. In addition, the address allocation responsemay carry the PDN configuration information, including a DNS serveraddress, a P-CSCF address, and an application server address.

Step 404: The PDN GW sends a policy control session update request thatcarries the UE IP address and data channel ID to the policy controlentity.

Step 405: The policy control entity may associate the data channel IDwith a previously established policy control session to update the IPaddress of the policy control session. The policy control entity mayalso update the policy control rule, including provision of data packetfilter and distribution information according to the IP address. Then,the policy control entity sends the updated policy control rule to thePDN GW.

Step 403 may be executed before or after step 404. Step 403 is optional.

In the preceding process, the UE accesses the same PDN. In step 401, noIP address is allocated to the UE, but an IP address is allocated to theUE in step 402 and step 403.

FIG. 5 is a schematic diagram illustrating a process of establishing adata connection in Embodiment 3 of the present invention. The processincludes the following steps:

Step 501: A UE establishes a data channel with an SGW. The SGW may alsoprovide a policy control entity with a data channel ID, and establish apolicy control session with the policy control entity to implementpolicy control on the data channel between the UE and the SGW. The datachannel ID includes a UE ID and an ID that is used for accessing thePDN. In the data connection setup process, the UE may also obtain theconnection related configuration information from the SGW, for example,the bearer control mode.

Step 502: The UE sends an address allocation request to the SGW,requesting the allocation of an IP address for accessing the PDN.

Step 503: The SGW sends a connection setup request, for example, a proxymobile IP (PMIP) binding update request, requesting the PDN GW toestablish an IP connection for the UE to access the PDN. The PDN GWallocates an IP address, including allocating an IP address by the PDNGW itself or through other servers and GWs.

Step 504: To establish a policy control session of the IP connectionwith the policy control entity, the PDN GW needs to obtain a relatedpolicy control rule.

Step 505: The PDN GW sends a connection setup ACK to the SGW, where theconnection setup ACK includes an address allocation response thatcarries the allocated IP address. In addition, the connection setup ACKmay carry the PDN configuration information sent to the UE, including aDNS server address, a P-CSCF address, and an application server address.

Step 506: If necessary, the SGW may initiate a process of updating orestablishing the policy control session of the IP connection to thepolicy control entity, including providing the policy control entitywith the connected IP address and the data channel ID.

Step 507: The SGW sends an address allocation response that carries theallocated IP address to the UE. In addition, the address allocationresponse may carry the PDN configuration information, including a DNSserver address, a P-CSCF address, and an application server address.

Step 506 may be executed before or after step 507. Step 507 is optional.In addition, if the SGW already establishes a session with the policycontrol entity in step 501, the policy control entity may also initiatea request for updating the policy control rule to the SGW afterreceiving the IP address in step 504. If the SGW does not establish asession with the policy control entity in step 501, the PDN GW mayestablish a policy control session of the IP connection with the policycontrol entity after the PDN GW establishes an IP connection for the UEto access the PDN. For details, see the description in Embodiment 1 ofthe present invention.

FIG. 6 is a schematic diagram illustrating a process of establishing adata connection in Embodiment 4 of the present invention. The processincludes the following steps:

Step 601: A UE sends a data channel setup request to an SGW, forexample, an attach request, where the data channel setup request doesnot request the allocation of an IP address.

Step 602: The SGW sends a data channel setup request to the PDN GW, forexample, a PMIP binding update request or a GTP create session request.The PDN GW establishes an IP connection for the UE to access the PDNaccording to the data channel setup request. The PDN GW allocates an IPaddress, including allocating an IP address by the PDN GW itself orthrough other servers and GWs.

Step 603: To establish a policy control session of the IP connectionwith a policy control entity, the PDN GW needs to obtain a relatedpolicy control rule.

Step 604: The PDN GW sends a data channel setup ACK to the SGW, wherethe data channel setup ACK includes an address allocation response thatcarries the allocated IP address. In addition, the data channel setupACK may carry the PDN configuration information sent to the UE,including a DNS server address, a P-CSCF address, and an applicationserver address.

Step 605: If necessary, the SGW may initiate a process of establishing apolicy control session of the IP connection to the policy controlentity, including providing the policy control entity with the connectedIP address.

Step 606: The SGW sends a data channel setup ACK to the UE, for example,an attach complete message, where the data channel setup ACK does notcarry the IP address allocated to the UE.

Step 607: The UE sends an address allocation request to the SGW or thePDN GW, requesting the allocation of an IP address.

Step 608: The SGW or the PDN GW sends an address allocation responsethat carries the allocated IP address to the UE. In addition, theaddress allocation response may carry the PDN configuration information,including a DNS server address, a P-CSCF address, and an applicationserver address.

If step 603 is omitted in the preceding process, the PDN GW does notestablish a policy control session with the policy control entity.

It is understandable to those skilled in the art that all or part of thesteps in the methods according to the preceding embodiments may beperformed by hardware instructed by a program. The program may be storedin a computer readable storage medium, such as a read-only memory/randomaccess memory (ROM/RAM), a magnetic disk, and a compact disk.

FIG. 7 shows architecture of a mobile network in an embodiment of thepresent invention. The mobile network includes a UE 710, a GW 720, and apolicy control entity 730.

The GW 720 is configured to: establish a data channel with the UE 710,and allocate an IP address to the UE according to the address allocationrequest or data channel setup request sent from the UE 710.

The policy control entity 730 is configured to establish or update apolicy control session according to the IP address provided by the GW720.

Specifically, the GW 720 includes a PDN GW and an SGW.

FIG. 8 shows a structure of a mobile network in Embodiment 4 of thepresent invention. The mobile network includes a UE 810, a PDN GW 820, apolicy control entity 830, and an SGW.

The PDN GW 820 includes:

a first allocating unit 821, configured to allocate an IP address to theUE 810 according to the address allocation request or the data channelsetup request sent from the UE 810, where the data channel setup requestdoes not request the allocation of an IP address; and

a first sending unit 822, configured to send a policy control sessionsetup request that carries the IP address allocated to the UE 810 to thepolicy control entity 830 according to the IP address allocated by thefirst allocating unit 821.

The first sending unit 822 of the PDN GW is further configured to send adata channel setup ACK to the SGW. The data channel setup ACK includesan address allocation response that carries the allocated IP address tothe SGW.

The SGW includes:

a sending unit, configured to send a policy control session setuprequest that carries the IP address to the policy control entityaccording to the IP address carried in the data channel setup ACK.

The policy control entity 830 includes:

a receiving unit 831, configured to receive a policy control sessionsetup request from the PDN GW 820 and/or the SGW; and

an establishing unit 832, configured to establish a policy controlsession according to the IP address that is allocated to the UE 810 andcarried in the policy control session request.

The first sending unit 822 of the PDN GW is further configured to sendan address allocation response that carries the allocated IP address tothe UE 810.

The address allocation response may further carry the PDN configurationinformation, including a DNS server address, a P-CSCF address, and anapplication server address.

FIG. 9 shows a structure of a mobile network in Embodiment 5 of thepresent invention. The mobile network includes a UE 910, a PDN GW 920,and a policy control entity 930.

The PDN GW 920 includes:

a second sending unit 922, configured to send a policy control sessionsetup request that carries a data channel ID to the policy controlentity 930, where the data channel ID includes a UE ID and an ID that isused for accessing the PDN.

The policy control entity 930 includes:

a receiving unit 931, configured to receive a policy control sessionsetup request from the PDN GW 920; and an establishing unit 932,configured to establish a policy control session according to the datachannel ID carried in the policy control session request.

The PDN GW 920 may further include:

a second allocating unit 921, configured to allocate an IP address tothe UE 910 according to the address allocation request sent from the UE910.

The second sending unit 922 is further configured to send a policycontrol session update request that carries the IP address to the policycontrol entity 930 according to the IP address allocated by the secondallocating unit 921.

The policy control entity 930 may further include an updating unit 933.

The receiving unit 931 is further configured to receive a policy controlsession update request that carries the IP address allocated to the UE910 and the data channel ID sent from the PDN GW 920.

The updating unit 933 is configured to: associate the data channel IDwith a previously established policy control session, and update the IPaddress and the policy control rule of the policy control session.

The policy control entity 930 may further include a sending unitconfigured to send the updated policy control rule to the PDN GW 920.

The second sending unit 922 is further configured to send an addressallocation response that carries the allocated IP address to the UE 910.

The address allocation response may further carry the PDN configurationinformation, including a DNS server address, a P-CSCF address, and anapplication server address.

FIG. 10 shows a structure of a mobile network in Embodiment 6 of thepresent invention. The mobile network includes a UE 1010, an SGW 1000, aPDN GW 1020, and a policy control entity 1030.

The SGW 1000 includes a sending unit 1001 configured to send a policycontrol session setup request that carries a data channel ID to thepolicy control entity 1030.

The policy control entity 1030 includes: a receiving unit 1031,configured to receive a policy control session setup request from theSGW 1000; and an establishing unit 1032, configured to establish apolicy control session according to the data channel ID carried in thepolicy control session request.

The sending unit 1001 of the SGW is further configured to send aconnection setup request sent from the UE 910 to the PDN GW 1020.

The PDN GW 1020 includes: a third allocating unit 1021, configured toallocate an IP address to the UE 1010 according to the connection setuprequest; and a third sending unit 1022, configured to send a policycontrol session update request that carries the IP address to the policycontrol entity 1030.

The receiving unit 1031 of the policy control entity 1030 is furtherconfigured to receive a policy control session update request thatcarries the IP address allocated to the UE 1010 and the data channel IDfrom the PDN GW 1020. The policy control entity 1030 further includes:an updating unit 1033, configured to associate the data channel ID witha previously established policy control session, and update the IPaddress and the policy control rule of the policy control session; and asending unit, configured to send the updated policy control rule to thePDN GW 1020 and the SGW 1000 according to the IP address carried in thepolicy control session update request.

The third sending unit 1022 of the PDN GW is further configured to senda connection setup ACK that includes an address allocation responsecarrying the allocated IP address to the SGW 1000. The sending unit 1001of the SGW is configured to send the address allocation response thatcarries the IP address to the UE 1010.

The sending unit 1001 of the SGW is further configured to send a policycontrol session update request that carries the IP address and the datachannel ID to the policy control entity 1030. The updating unit 1033 ofthe policy control entity is further configured to update the policycontrol rule corresponding to the data channel ID according to the IPaddress carried in the policy control session update request, and sendthe updated policy control rule to the SGW 1000 through the sendingunit. The address allocation response may further carry the PDNconfiguration information, including a DNS server address, a P-CSCFaddress, and an application server address.

As shown in FIG. 8, a policy control entity provided in Embodiment 7 ofthe present invention includes a receiving unit 831 and an establishingunit 832.

The receiving unit 831 is configured to receive a policy control sessionsetup request that carries a data channel ID from the GW.

The establishing unit 832 is configured to establish a policy controlsession according to the data channel ID carried in the policy controlsession request.

As shown in FIG. 9, a policy control entity provided in Embodiment 8 ofthe present invention includes a receiving unit 931, an establishingunit 932, and an updating unit 933.

The receiving unit 931 is configured to receive a policy control sessionsetup request that carries a data channel ID sent from the GW, andreceive a policy control session update request that carries an IPaddress allocated to the UE and a data channel ID sent from the GW.

The establishing unit 932 is configured to establish a policy controlsession according to the data channel ID carried in the policy controlsession request.

The updating unit 933 is configured to: associate the data channel IDwith a previously established policy control session, and update the IPaddress of the policy control session and the policy control rule.

In addition, the policy control entity may include a sending unitconfigured to send an initial policy control rule and an updated policycontrol rule to the GW.

Thus, by using the method for establishing data connections, the mobilenetwork, and the policy control entity provided in embodiments of thepresent invention, after a data channel is established between the UEand the GW, the GW triggers the policy control entity to establish orupdate the policy control session. When the UE obtains an IP addressthrough the PDN GW, the PDN GW establishes or updates the policy controlsession; or when the UE obtains an IP address through the SGW, the SGWestablishes a mobile IP connection with the PDN GW and then establishesor updates the policy control session. In embodiments of the presentinvention, the policy control can still be implemented when the UE doesnot request the allocation of an IP address. Thus, embodiments of thepresent invention are applicable to the GTP protocol and the mobile IPprotocol.

Detailed above are a method for establishing data connections, a mobilenetwork, and a policy control entity under the present invention.Although the invention is described through several exemplaryembodiments, the invention is not limited to such embodiments. It isapparent that those skilled in the art can make various modificationsand variations to the invention without departing from the scope of theinvention. The invention shall cover the modifications and variationsprovided that they fall within the scope of protection defined by thefollowing claims or their equivalents.

1. A method for establishing data connections on a mobile network,comprising: establishing a data channel between a user equipment (UE)and a gateway (GW); allocating an Internet Protocol (IP) address to theUE accordi ng to an address allocation request or a data channel setuprequest sent from the UE; and sending a policy control session setup orupdate request carrying the IP address to a policy control entity sothat the policy control entity establishes or updates a policy controlsession according to the policy control session setup or update request.2. The method of claim 1, wherein the step of establishing the datachannel between the UE and the GW comprises: establishing a data channelbetween the UE and a packet data network (PDN) GW.
 3. The method ofclaim 2, wherein the step of establishing the policy control session bythe policy control entity according to the policy control session setuprequest comprises: receiving a policy control session setup request thatcarries the IP address from the PDN GW; and establishing a policycontrol session according to the IP address.
 4. The method of claim 2,wherein: before the step of allocating the IP address to the UEaccording to the address allocation request sent from the UE, the methodfurther comprises: establishing, by the policy control entity, a policycontrol session according to a data channel ID provided by the PDN GW;the step of updating the policy control session by the policy controlentity according to the policy control session update request comprises:receiving a policy control session update request that carries the IPaddress from the PDN GW; and updating a policy control rulecorresponding to the policy control session according to the IP address.5. The method of claim 1, wherein the step of establishing the datachannel between the UE and the GW comprises: establishing a data channelbetween the UE, a serving gateway (SGW), and a packet data network (PDN)GW.
 6. The method of claim 5, wherein: before the step of allocating theIP address to the UE according to the address allocation request sentfrom the UE, the method further comprises: establishing, by the policycontrol entity, a policy control session according to a data channel IDprovided by the SGW; the step of updating the policy control session bythe policy control entity according to the policy control session updaterequest comprises: sending, by the SGW, a policy control session updaterequest that carries the IP address to the policy control entity; andupdating, by the policy control entity, a policy control rulecorresponding to the policy control session according to the IP address.7. The method of claim 6, wherein the step of allocating the IP addressto the UE according to the address allocation request sent from the UEcomprises: sending, by the SGW, a connection setup request that carriesan address allocation request instruction to the PDN GW; by the PDN GW,allocating an IP address to the U E according to the address allocationrequest instruction, and sending a connection setup ACK that carries theIP address to the SGW; and sending, by the SGW, an address allocationresponse that carries the IP address to the UE.
 8. The method of claim7, wherein the step of updating the policy control session by the policycontrol entity according to the policy control session update requestcomprises: receiving a policy control session update request thatcarries the IP address allocated to the UE and a data channel ID sentfrom the PDN GW; and updating the policy control rule corresponding tothe data channel ID according to the IP address.
 9. The method of claim8, wherein after the step of updating the policy control rulecorresponding to the policy control session according to the IP address,the method further comprises: sending, by the policy control entity, anupdated policy control rule to the SGW.
 10. The method of claim 5,wherein the step of allocating the IP address to the UE according to thedata channel setup request comprises: receiving, by the SGW, a datachannel setup request that does not carry an address allocation requestinstruction from the UE; sending, by the SGW, the data channel setuprequest to the PDN GW; and by the PDN GW, establishing a data channeland allocating an IP address to the UE according to the data channelsetup request, and sending a data channel setup ACK that carries theallocated IP address to the SGW.
 11. The method of claim 10, wherein thestep of establishing the policy control session by the policy controlentity according to the policy control session setup request comprises:sending, by the PDN GW and/or the SGW, a policy control session setuprequest that carries the IP address allocated to the UE to the policycontrol entity; and establishing, by the policy control entity, a policycontrol session according to the IP address.
 12. The method of claim 11,wherein after the policy control entity establishes the policy controlsession according to the policy control session setup request, themethod further comprises: sending, by the SGW, a data channel setup ACKthat does not carry the IP address allocated to the UE to the UE;sending, by the UE, an address allocation request to the SGW or the PDNGW to request the allocation of an IP address; and sending, by the SGWor the PDN GW, an address allocation response that carries the IPaddress to the UE.
 13. The method of claim 4, wherein the data channelID comprises a UE ID or an ID that is used for accessing the PDN. 14.The method of claim 6, wherein the data channel ID comprises a UE ID oran ID that is used for accessing the PDN
 15. A policy control entity,comprising: a receiving unit, configured to receive a policy controlsession setup or update request that carries an Internet Protocol (IP)address allocated to a user equipment (UE) from a gateway (GW); anestablishing unit, configured to establish a policy control sessionaccording to the policy control session setup request; and an updatingunit, configured to update the IP address and a policy control rule ofthe policy control session according to the policy control sessionupdate request.
 16. The policy control entity of claim 15, furthercomprising: a sending unit, configured to send the updated policycontrol rule to the GW according to the IP address carried in the policycontrol session update request.
 17. A mobile network, comprising: agateway (GW), configured to: establish a data channel between a userequipment (UE) and the GW, allocate an Internet Protocol (IP) address tothe UE according to an address allocation request or a data channelsetup request sent from the UE, and send a policy control session setupor update request that carries the IP address to a policy controlentity; and the policy control entity, configured to establish or updatea policy control session according to the policy control session setupor update request from the GW.
 18. The mobile network of claim 17,wherein: the GW comprises a packet data network (PDN) GW, and the PDN GWcomprises: a first allocating unit, configured to allocate an IP addressto the UE according to the address allocation request or the datachannel setup request sent from the UE, wherein the data channel setuprequest does not carry an address allocation instruction; and a firstsending unit, configured to send a policy control session setup requestthat carries the IP address allocated to the UE to the policy controlentity; the policy control entity comprises: a receiving unit,configured to receive the policy control session setup request; and anestablishing unit, configured to establish a policy control sessionaccording to the IP address that is allocated to the UE and carried inthe policy control session request.
 19. The mobile network of claim 18,further comprising a serving gateway (SGW), wherein: the first sendingunit of the PDN GW is further configured to send a data channel setupACK that carries the allocated IP address to the SGW; and the SGWcomprises: a second sending unit, configured to send a policy controlsession setup request that carries the IP address to the policy controlentity according to the IP address carried in the data channel setupACK.
 20. The mobile network of claim 19, wherein: the PDN GW furthercomprises: a second allocating unit, configured to allocate an IPaddress to the UE according to the address allocation request sent fromthe UE; the first sending unit is further configured to send a policycontrol session update request that carries the IP address to the policycontrol entity according to the IP address allocated by the secondallocating unit; the policy control entity further comprises an updatingunit configured to update the IP address and policy control rule of thepolicy control session; and the receiving unit of the policy controlentity is further configured to receive a policy control session updaterequest from the PDN GW, wherein the policy control session updaterequest carries the IP address allocated to the UE and a data channelID.
 21. The mobile network of claim 20, wherein: the SGW is furtherconfigured to: send a connection setup request that carries an addressallocation request instruction to the PDN GW, and send a policy controlsession update request that carries the IP address and the data channelID to the policy control entity; and the PDN GW is configured to:allocate the IP address to the UE according to the address allocationrequest instruction carried in the connection setup request, and send aconnection setup ACK that carries the IP address allocated to the UE tothe SGW; the receiving unit of the policy control entity is furtherconfigured to receive a policy control session update request thatcarries the IP address allocated to the UE and the data channel ID fromthe SGW; and the updating unit is further configured to update a policycontrol session corresponding to the data channel ID according to the IPaddress carried in the policy control session update request.
 22. Themobile network of claim 20, wherein: the PDN GW is further configured tosend a policy control session update request that carries the IP addressto the policy control entity; and the receiving unit of the policycontrol entity is further configured to receive a policy control sessionupdate request that carries the IP address allocated to the UE and thedata channel ID from the PDN GW; and the policy control entity furthercomprises an updating unit configured to: associate the data channel IDwith a previously established policy control session, and update the IPaddress and the policy control rule of the policy control session.